Apparatus and method for pulping paper stock



" 4, 1955 G. B. FOWLER APPARATUS AND METHOD FOR PULPING PAPER STOCK 3 Sheets-Sheet 1 Filed Sept. 14, 1955 JIVVENTOR. Ju aye A W m, 4, 1955 G. B. FOWLER 2,719,452

APPARATUS AND METHOD FOR PULPING PAPER STOCK Filed Sept. 14., 1955 3 Sheets-Sheet 2 IN V EN TOR. 1% 5. 1

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5 Sheets-Sheet 3 R E L W O F B G APPARATUS AND METHOD FOR PULPING PAPER STOCK Filed Sept. 14, 1955 2,719,462 Patented Dot. 4, 1955 APPARATUS AND METHGD FOR PULPING PAPER STOCK George B. Fowler, Blandford, Mass. Application September 14, 1953, Serial No. 379,808

9 Claims. (Cl. 9225) The present invention relates to an apparatus and method for making paper stock from raw materials as rags, broke, and, in general, defiberizable cellulosic materials such as may be converted into a pulp suitable for the production of paper and pulp products.

By reason of its special construction and mode of operation it is particularly well suited for the conversion of cotton rags into high grade half-stock, which may then be converted into suitable furnishes capable of being run off on a Fourdrinier machine. The apparatus is also very well adapted for the washing of pul as it lends itself to the ready association with one or more of the usual type of water-removing washing cylinders.

The invention has for its particular object the adaptation of an already known special type of fiber-comrninuting instrumentality which has hitherto been employed, but

in a different setting or environment, for the breaking up of paper broke and the like. Its adaptation to a more or less standard type of paper beater tub has, however, not proved successful, until the advent of the present invention which makes this device highly operative in a divided tub such as is used with paper heaters or washers.

Accordingly it is a further object of the invention to provide means for more effectively directing paper stock while in aqueous suspension into a pulping and disintegrating mechanism rapidly rotating about a vertical axis, and located at the bottom of one end of a longitudinaliy divided paper beater tub.

A further object of the invention is to provide means whereby stock which has contacted, and has been acted upon, by said mechanism, Will be re-directed in a manner to cause it to be again and again acted upon, while a portion of the stock is permitted to escape and, by its direction and momentum, to achieve efiicient circulation of the pulp in the beater tub.

A still further object of the present invention is to modify a horizontally disposed type of paper beater tub, so as to make it more useful and operative in connection with a cutting and pulping apparatus which rotates on a vertical axis at one end of such a beater tub.

Other objects of the present invention will become apparent from the further description hereinbelow, from the accompanying drawings, and the claims.

In the drawings:

Fig. l is a top plan view of a beater tub and the papercomminuting device mounted therein;

Fig. 2 is a vertical partial section taken along the line 2-2 of Fig. 1;

Fig. 3 is a vertical 3-3 of Fig. 2;

Fig. 4 is a vertical cross-section taken along the line 44 of Fig. 1 and looking toward the rear of the beater tub;

Fig. 5 is a plan view of the forward portion of the beater tub, on a somewhat enlarged scale as compared with the previous figures;

Fig. 6 is a vertical cross section along lines 6-6 of partial section taken along the line Fig. 5, looking from the front toward the rear of the beater tub; and

Fig. 7 is a similar section to that of Fig. 6, but looking obliquely toward the front end of the beater tub, along line 7-7 of Fig. 5.

The apparatus of the present invention comprises an elongated or horizontally disposed type of beater tub generally designated by the reference numeral 8, and comprising the usual side walls 9 and 10, a rounded front end 11 and a rounded rear end 12. The heater tub is divided into two reaches (using this word in the sense of the uninterrupted stretch of a stream) by a dividing partition 13 usually termed, in this art, as the midfeather. The reach 14 leads toward the front end of the beater tub and reach 15 toward the rear end; there are also provided the usual drain openings 16 and 17 and the sand-trap 18 in the floor of the reach 15; the former being closed by the usual covers 19 (19 is seen only on Fig. 3), these covers being removed when the tub is drained at the end of the operation. In referring to the beater it should be understood that the usual roll and bed plate has been removed, as superfluous in view of the present invention.

Contrary to the usual practice, the fioor of the beater tub is not level, but starts gradually sloping upwardly as the pulp moves along reach 15 toward the rear 12 of the tub, the floor in reach 14 sloping still further as the pulp then moves toward the front end of the tub, these movements being shown in the form of arrows in the two reaches in question. As it is contemplate-d that the pulp will be kept at about the water-level line 20, there will be less depth of pulp at the forward end of reach 14. Therefore as the flowing mass of pulp passes over the inclined portion 21 of the floor of reach 14, it will fall over the edge 22 as water does over the rim of a waterfall, and hence will encounter the pulping instrumentality broadly designated by the reference numeral 23 and located in the pit or chamber 24 and rotated by means of a shaft (not shown) but which passes through the floor portion of the pit to a suitable drive. As this drive and the pulping instrumentality is not, by itself, new, and is adequately described in patents to Edwin Cowles, for instance Nos. 2,351,492 and 2,557,174, its details need not be fully illustrated. Moreover, this pulping instrumentality, which for sake of avoiding circumlocution in the rest of this specification will be termed the pulper, is also described and Well illustrated in a printed publication entitled Cowles Beatapulper, issued by The Cowles Company, Inc, of Cayuga, New York.

For the purposes of understanding the present invention this pulper is shown as having a bed-plate 26 above which rotates the comminuting portion of the device comprising a set of radially obliquely extending knives 27 and curved impeller blades 28, which serve to hurl pulp and liquid coming in contact therewith tangentially outwardly at a high speed. On its travel from the impeller blades 28 the pulp encounters the knives 27, and as the bed plate is provided with numerous grooves, thereby comminutes or cuts up the stock, such as rags, and divides it into individual fibres. Much in the same manner as does the knife roll of a regular beater, the stock or pulp is thereby fibrillated and partially hydrated. This action is, in accordance with the present invention, greatly improved by providing positive means whereby to assure that the pulp stock makes repeated contact with the pulper; while at the same time the motion imparted to the pulp by the impeller thereon is utilized to eifect the proper circulation of the stock in the two reaches of the beater.

The first effect upon the stock which tumbles down Under the centrifugal force the stock discharges tangentially. Were there no special provision, it would merely flow out to the surrounding edges, and would set up a vortex, but there would. be no discharge of the treated pulp back into the reach of the. beater, so that there would be no. circulation. In other words, the stock would be merely carried around and around the pulper without accomplishing very much.

In accordance with the improvement which. is the essence of the present inventiomthe outwardly tangentially moving pulp stock is caused to impinge a number of specially positioned baflles which return portions of the stock substantially inwardly and downwardly toward the center of the pulper 23. The firstv of these baffles is at the front end of the beater. Thus baffle 24 intercepts the stock and turns it back, inv the general direction: of arrow a toward the center of the pulper to be further acted upon. As the stockv swirls around. the pulper 23 some of the peripheral portions of it. encounter the domelike bathe 2'9 and as a result have their direction changed so that a strong stream of stock will be thrown in the direction of'arrow 5 into the throat 30 of the reach-15, thus being ejected therethrough. with the result that a good circulation of. stock in both reaches of the beater tub ensues. Another portion of the mass of stock which forms the vortex surrounding the pulper 23 is intercepted by the baflle 32 whichis faired at its highest end to the thickened mid-feather portion 31 ofthe mid-feather 13 of the tub, and is thus again brought under the action of the pulper 23. The portion going into the throat 30 takes the general direction of arrow 0, while that actedupon by bafiie 32 returns along. the general direction of arrow d.

As the stock is ejected into throat 30 of reach 15, it will be at an elevation relative to the general water level and this further improves. the circulation.

There is thus effected a very complete circulation of the stock and the assurance that it is constantly being returned to the pulper 23.

It will be noticed that the mid-feather 13 of the beater is thickened at the part 31 and that the baffle 32 starts at the top of this portion and decreases inheight along a rather steep slope preferably so curved as topresent a convex line relative to the beater base.

When observing the. apparatus in action one can see a main cascade of pulp falling over the edge 22 into the pulper; a second, somewhat narrower stream flowing first outwardly against bafde 2'4 and thenv vaulting upwardly and then turning downwardly and being directed substantiall'y toward-the center of the pulper; while a third stream, coming from the surface of dome 29, will fiow with violent motion as a strong. turbulent stream intothroat 30, but diminishes somewhat in velocity as it widens outinto the calmer reaches of reach 15.

These bafilling means are of extreme importance and contribute to avery marked extent to the success of the operation, for without some means for returning considerable of the stock to the pulper, while yet permitting some to escape and furnish the necessary impetus to effect proper circulation, the stock would simply churn around in a vortex immediately above the impeller of the pulper, and while this might eventually cut up and defiber the stock in the vortex or pulping chamber, it would leave most of the stock in the form of quiescent or at least substantially motionless pulp masses, especially in reach 15 of the beater.

Inasmuch as beaters or washers of the general types illustrated, and which have for many years been known as the Hollander type, are to be found in: substantial numbers in almost every paper mill, it makes possible the efiicien't application of the Cowles type of pulping mechanism by enabling its installation in such units.

According. to the above mentioned two Cowles patents, the impeller disc. is mounted in specialtanks, which may be either circular in cross section as those shown in Patent No. 2,351,492, where the impeller is located coincidentalwith the center of the tank, or as in Patent No. 2,557,174, where it is located between the wall and the center. Then, again, as in the circular put out by the Cowles Company, already mentioned, the impeller is actually in the side of a specially shaped tank and operates on a horizontal axis. Such equipment is foreign to the normally available equipment in paper plants, and would require special, and expensive, installations. Moreover, the type of tanks suggested in these Cowles patents and publication would necessarily extendmuch higher above the floor level than are the standard types of beater, the tops of which are normally at a convenient height, so that operators can properly and easily feed them and observe their operation from floor level.

An apparatus constructed in accordance with applicants principles, also lends itself very well to the use of screened or washing cylinders, one or more of whichmay be lowered into either of the two reaches (preferably reach 14) to constantly or intermittently dip water out of the stock. while more water is admitted from a pipe or hose, so as gradually to change the water, thus washing.

the stock. In the tanks suggested in the Cowles patents and publication, the. useofsuch de-watering screens would be counter-indicated, if not impossible. Therefore, the. present construction enables considerable efficiency, economies a d ease of operation.

The essential novelty claimedfor the present invention,

lies in the positioning. of the pulping mechanism or disc in a well or pit at the head or front end of a two-reach paper beater tub, together with means for selectively discharging the stream of the stock into the said pulper mechanism or disc and additionalmeans for directing some of the material back into the said mechanism or disc while 7 at the same time letting enough of it escape to insure the proper ejection force to insure efficient circulation of the main mass of pulp or stock.

The beater tub. may be in the form of a woodengtank, lined with some non-corroding metal such as stainless steel, copper, tinned iron, or plastic; or it may be made. directly of some non-rusting metal such as stainless steel, copper, Monel metal, aluminum, or the like. The space between the wall 10 of the beater and the inner wall of the throat 36' may be filled with: any suitable material,

such as concrete, or he left empty, providing only that the narrowed effect of the throat is secured.

The pulper mechanism or disc may be made of any suitable metal. or metals, and it may be driven from. a vertical shaft passing through the bottom of the beater, and there driveneither through a suitable reducing, gear or by means of pulleys andbelts. As all such devices are fully Well known, and form no part of the inventive features of the construction shown, they are not illustrated, as they are fully within. the skill of the art.

The bafiles, also, may be made of any suitable material,

such as is used in the construction of the beater itself and of its. mid-feather.-

Applicant claims:

1. In. an apparatus for. d'efi-beri-ng paper stock in which a defiberizing instrumenta-lity rotatesina pulping chamher about a vertical axis at the bottom of one side of a; Hollander type of beater tub, the improvements which comprise means for discharging circulating stock into said instrumentality from a level. substantial-1y above the 2. Method of defiberizing paper. stock which comprises dischargingv said stock while in aqueous suspension downwardly into a pulping mechanism rotating on a vertical axis, peripherally discharging said stock from said mechanism and effecting the return of most of it into the said mechanism by curved vertically extending baffles, the contact surface portions of which are curved so as to cause the stock to flow in an inward and downward direction, said baffles being arranged to produce a plurality of such deflected streams.

3. Method of defiberizing paper stock which comprises dropping an aqueous suspension of said stock downwardly onto a defiberizing apparatus rapidly rotating about a vertical axis and provided with knives and a therewith cooperating bed plate and from which a stream of suspended stock is peripherally discharged, and intercepting and subdividing said stream into a plurality of streams directed backwardly and downwardly into said apparatus to again be subjected to its defiberizing action.

4. An apparatus for defiben'zing paper stock which comprises the combination of a beater tub having a dividing wall and a rotary defiberizing means at one end thereof and fed with aqueously suspended paper stock by having the same spill into said means from a locus above it; and means for deflecting a major portion of stock peripherally discharged by said means back into said means while permitting escape of the rest of said discharged stock at high velocity into the discharge side of the beater tub whereby to circulate the stock therein.

5. In an apparatus for defiberizing paper stock and comprising the combination of a divided paper beater tub and a stock-comminuting and fiberizing means at one end thereof and rotating on a vertical axis and discharging aqueously suspended paper stock peripherally therefrom, the improvements which comprise curved baflies located so as to cause said suspended stock to flow inwardly and downwardly into said fiberizing means, and some of the stock outwardly and forwardly.

6. A paper beater comprising an elongated roundended tub divided into two parallel longitudinally extending reaches connected at one end by an unimpaired curved passageway, at least one of said reaches having an upwardly inclined bottom terminating before the other end of said tub, whereby to cascade aqueously suspended stock into a chamber having a bottom substantially coplanar with the bottom of the other reach of said tub; a horizontally rotating fiberizing disc rapidly rotatable in said chamher and having means thereon for tangentially and peripherally discharging pulped stock therefrom when such stock is cascaded thereinto from the aforementioned inclined bottom; a first bafile on the rounded end wall of said tub located concentrically of the axis of said rotating disc and curved to return stock discharged therefrom substantially toward the center of said disc, and a second battle intercepting other portions of the discharged stock and returning a portion of it to the disc while permitting escape of the rest of the stock, a narrowed throat-portion into which said discharged stock is directed and which portion widens out and becomes a part of the other reach above mentioned, whereby stock is kept in eflicient circulation in said tub and brought repeatedly into contact with said disc.

7. Method of defiberizing paper stock in a divided paper beater tub which comprises cascading said stock while in aqueous suspension from one reach of said tub into the vortex created by the rapid rotation of a fiberiz ing disc rotating on a horizontal axis at one end of said tub, and having means thereon for peripherally discharging said stock at high speed, and intercepting separate portions of the stock thus discharged and directing them back in an inward and downward direction into said vortex, while permitting a portion of the stock to travel substantially horizontally outwardly along the other reach of said beater tub and thence through the first mentioned reach back to the place where the stock is cascaded into said vortex.

8. A paper-pulp making apparatus which comprises a beater tub having two reaches divided by a mid-feather, at least one reach having an upwardly sloping bottom, a pit at the forward end of the tub into which paper stock in aqueous suspension is discharged from the upward end of the sloping bottom, a cutting and fiberizing mechanism located at the bottom of said pit and capable of rapid rotation about a vertical axis; a series of baffles surrounding said mechanism, one being placed so as to intercept a portion of stock returning to said fiberizing mechanism and project same toward the center of said mechanism; a second baflie positioned so as to direct stock out of the pit into the other reach of the beater, and a sloping intercepting baffle dividing the discharged stream and directing a substantial portion thereof back into said mechanism, said last-mentioned bafiie connected to and thereby made part of the mid-feather of the beater.

9. A pulping apparatus particularly adapted to the defiberization of paper stock which comprises the combination of a longitudinally divided tub of the Hollander beater type having at one end a pulping mechanism rapidly rotating about a vertical axis and capable of discharging aqueously suspended paper stock longitudinally from its periphery, and means for intercepting portions of the stock so discharged and directing them back into the vortex swirling around said mechanism, and means for directing another portion of said stock at considerable velocity into one side of said tub to enable it to circulate back to the other side thereof and thereby again to be brought into contact with said pulping mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 1,233,164 Bahr July 10, 1917 2,452,399 Stadler Oct. 26, 1948 FOREIGN PATENTS 746 Great Britain 1887 453,451 Great Britain Sept. 11, 1936 

1. IN AN APPARATUS FOR DEFIBERING PAPER STOCK IN WHICH A DEFIBERIZING INSTRUMENTALITY ROTATES IN A PULPING CHAMBER ABOUT A VERTICAL AXIS AT THE BOTTOM OF ONE SIDE OF A HOLLANDER TYPE OF BEATER TUB, THE IMPROVEMENTS WHICH COMPRISE MEANS FOR DISCHARGING CIRCULATING STOCK INTO SAID INSTRUMENTALITY FROM A LEVEL SUBSTANTIALLY ABOVE THE UPPER SURFACE THEREOF AND WHICH MEANS COMPRISE AN UPWARDLY SLANTING FLOOR IN SAID HOLLANDER TUB, AND BAFFLE MEANS LOCATED AROUND AND EXTENDING FROM THE PERIPHERY OF THE SAID PULPING CHAMBER TO EFFECT RETURN OF PARTLY DEFIBERIZED STOCK IN A PLURALITY OF VORTICALLY TRAVELING STREAMS TO THE DEFIBERIZING INSTRUMENTALITY, AND A RELATIVELY NARROW DISCHARGE OPENING THROUGH WHICH STOCK WHICH HAS CONTACTED THE DEFIBERIZER IS DISCHARGED AT MAXIMUM SPEED OF TRAVEL INTO THE DISCHARGE REACH OF THE HOLLANDER. 